New NethServer::Password module implementation. Refs #2063

Replaces and obsoletes esmith::util::genRandomPassword() and
esmith::util::genRandomHash(). Digest::SHA1 module is no longer
required. The default path to store passwords is

  /var/lib/nethserver/secrets/
Password characters restricted to [A-Za-z0-9_]. Refs #2063
Remove terminal escape sequences from system logs